Polyisocyanate Fractionation via Selective Membrane
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Solution Overview
Problem
Current methods for producing polyisocyanates, such as phosgenation followed by distillation, result in the formation of higher molecular weight impurities, require complex equipment and significant energy, and are economically inefficient, leading to issues with product quality and operational complexity.
Innovation Solution
A membrane-based process for fractionating polyisocyanate mixtures in the liquid phase using selectively permeable membranes to separate the mixture into streams with different compositions, reducing the amount of free diisocyanate in prepolymers and avoiding the formation of additional higher molecular weight species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to separate polyisocyanates, then separation into different molecular weight fractions is achieved, but higher molecular weight impurities are formed and energy consumption increases
Solution Approach 1:
The invention changes the separation parameter from thermal (distillation) to mechanical/physical (membrane filtration). By using membranes with specific pore sizes, the process separates polyisocyanates based on molecular size without the high temperatures that cause polymerization and formation of higher molecular weight impurities.
Solution Approach 2:
The invention replaces the thermal-mechanical distillation system with a membrane-based separation system. The membrane acts as a selective barrier that physically separates molecules based on size, eliminating the need for heat-induced separation that causes harmful side reactions.
2Manufacturing precision
If distillation is used to separate polyisocyanates, then separation into different molecular weight fractions is achieved, but equipment complexity and energy consumption increase
Solution Approach 1:
The invention replaces complex thermal distillation equipment with simpler membrane filtration units. The membrane module consists of basic filtration components rather than complex distillation columns, condensers, and heating systems, significantly reducing equipment complexity.
Solution Approach 2:
The invention changes the separation mechanism from thermal gradients to physical filtration. This parameter change allows the use of simple pressure-driven membrane systems instead of energy-intensive distillation equipment, reducing both complexity and energy requirements.
3Productivity
If phosgenation is used to produce polyisocyanates, then production volume is increased, but higher molecular weight by-products are formed
Solution Approach 1:
The invention extracts and removes higher molecular weight by-products from the phosgenation mixture using membrane filtration. The membrane selectively retains larger molecules while allowing smaller desired polyisocyanates to pass through, effectively separating the harmful by-products from the desired product.
Solution Approach 2:
The invention converts the presence of higher molecular weight by-products from a harmful factor into a separation opportunity. By using these by-products as retention markers in the membrane process, the system efficiently identifies and separates unwanted components while recovering valuable lower molecular weight polyisocyanates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the efficient separation of polyisocyanates into distinct streams with reduced operating costs and simpler equipment, improving product quality by minimizing the presence of higher molecular weight impurities and free diisocyanates, thus enhancing the production process.
Implementation Method 1
fractionating a mixture of polyisocyanates in the liquid phase by means of a selectively permeable membrane
Implementation Method 2
A membrane-based process for fractionating polyisocyanate mixtures in the liquid phase using selectively permeable membranes to separate the mixture into streams with different compositions
Data Source
AI summary
Method of fractionating a mixture of polyisocyanates in the liquid phase, optionally in the presence of a suitable solvent or mixture of two or more solvents, by means of a selectively permeable membrane into a permeate stream and a retentate stream of polyisocyanate compositions different to each other and different to the original mixture.